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niumooniumoo
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feat: 增加热点代码
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‎pom.xml‎

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<module>tool-java-object-pool</module>
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<module>tool-java-jackson</module>
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<module>tool-java-apache-common</module>
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<module>tool-java-hotcode</module>
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</modules>
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<name>parent-modules</name>
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<description>Parent for all java modules</description>

‎tool-java-hotcode/pom.xml‎

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<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
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<parent>
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<artifactId>parent-modules</artifactId>
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<groupId>com.wdbyte</groupId>
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<version>1.0.0-SNAPSHOT</version>
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</parent>
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<modelVersion>4.0.0</modelVersion>
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<artifactId>tool-java-hotcode</artifactId>
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<properties>
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<maven.compiler.source>17</maven.compiler.source>
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<maven.compiler.target>17</maven.compiler.target>
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</properties>
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</project>

‎tool-java-hotcode/src/main/java/com/wdbyte/hotcode/HotCode.java‎

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package com.wdbyte.hotcode;
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import java.util.ArrayList;
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import java.util.HashSet;
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import java.util.List;
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import java.util.concurrent.ExecutorService;
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import java.util.concurrent.Executors;
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/**
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* @author niulang
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* @date 2023/02/20
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*/
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public class HotCode {
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private static HashSet hashSet = new HashSet();
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/**
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* 线程池，大小1
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*/
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private static ExecutorService executorService = Executors.newFixedThreadPool(1);
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public static void main(String[] args) {
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// 模拟 CPU 过高
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//cpuHigh();
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// 模拟线程阻塞，线程池容量为1，塞入两个线程，会有一个一直等待
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thread();
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// 模拟线程死锁
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deadThread();
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// 不断的向 hashSet 集合增加数据，内存缓慢增长
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addHashSetThread();
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// 生成大长度数组
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allocate();
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}
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private static Object array;
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/**
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* 生成大长度数组
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*/
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private static void allocate() {
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new Thread(() -> {
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int index = 1;
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while (true) {
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Thread.currentThread().setName("memory_allocate_thread");
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array = new int[1 * index * 1000];
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array = new Integer[1 * index * 1000];
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try {
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Thread.sleep(1000);
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} catch (InterruptedException e) {
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throw new RuntimeException(e);
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}
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index++;
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}
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}).start();
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new Thread(()->{
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List<String> list = new ArrayList<>();
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for (int i = 0; i < 1000000; i++) {
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try {
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Thread.sleep(1);
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} catch (InterruptedException e) {
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throw new RuntimeException(e);
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}
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list.add("string" + i);
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}
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}).start();
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}
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/**
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* 不断的向 hashSet 集合添加数据，每秒100个字符串
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*/
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public static void addHashSetThread() {
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// 初始化常量
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new Thread(() -> {
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int count = 0;
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while (true) {
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Thread.currentThread().setName("add_hash_set_thread");
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try {
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hashSet.add("count" + count);
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Thread.sleep(10);
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count++;
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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}
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}).start();
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}
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/**
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* 极度消耗CPU的线程
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* 死循环
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*/
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private static void cpuHigh() {
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Thread thread = new Thread(() -> {
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double pi = 0;
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for (int i = 0; i < Integer.MAX_VALUE; i++) {
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pi += Math.pow(-1, i) / (2 * i + 1);
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}
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System.out.println("Pi: " + pi * 4);
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});
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thread.start();
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}
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/**
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* 模拟线程阻塞
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* 线程池容量为1，但是向线程池中塞入两个线程
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*/
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private static void thread() {
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Thread thread = new Thread(() -> {
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while (true) {
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System.out.println("executorService thread start");
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try {
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Thread.sleep(1000);
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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}
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});
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// 添加到线程
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executorService.submit(thread);
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executorService.submit(thread);
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}
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/**
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* 死锁线程
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* 线程 dead_thread_A 与 线程 dead_thread_B 互相锁死
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*/
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private static void deadThread() {
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/** 创建资源 */
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Object resourceA = new Object();
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Object resourceB = new Object();
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// 创建线程
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Thread threadA = new Thread(() -> {
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Thread.currentThread().setName("dead_thread_A");
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synchronized (resourceA) {
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System.out.println(Thread.currentThread() + " get ResourceA");
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try {
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Thread.sleep(1000);
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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System.out.println(Thread.currentThread() + "waiting get resourceB");
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synchronized (resourceB) {
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System.out.println(Thread.currentThread() + " get resourceB");
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}
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}
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});
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Thread threadB = new Thread(() -> {
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Thread.currentThread().setName("dead_thread_A");
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synchronized (resourceB) {
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System.out.println(Thread.currentThread() + " get ResourceB");
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try {
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Thread.sleep(1000);
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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System.out.println(Thread.currentThread() + "waiting get resourceA");
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synchronized (resourceA) {
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System.out.println(Thread.currentThread() + " get resourceA");
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}
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}
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});
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threadA.start();
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threadB.start();
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}
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}

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